Trestle



April 13, 1965 D. E. GOODALE 3,173,145

TRESTLE Filed April 10, 1963 2 Sheets-Sheet 1 INVENTOR.

\ o. E. GOODALE ATTORNEY April 13, 1965 D. E. GOODALE 3,173,145

TRESTLE Filed April 10, 1965 2 Sheets-Sheet 2 FIG. 3 v FIG. 4

INVENTOR. D. E. GOODALE wgw ATTORNEY United States Patent "ice 3,178,146TRFSTLE Darrell E. Goodale, Davenport, Iowa, assignor to Ever-Tito Mfg.Co., Davenport, Iowa Filed Apr. 10, 1963, Ser. No. 271,981 1 Claim. (Cl.248352) This invention relates to a trestle of the vertically adjustabletype such as are commonly used for supporting elevated structures suchas motor vehicles and the like in storage, while being repaired, etc.More particularly, the invention relates to and has for its principalobject the provision of improved locking means for positively preventinginadvertent or accidental collapse of the supporting column after onceset in supporting position.

Various efforts have been made in the trestle art generally along theselines but so far no completely satisfactory means has been developed.Known devices fail because of defects in basic design, tendency torelease because of minor maltreatment, difliculty in enabling deliberaterelease when required and so on. The improved design of the presentinvention eliminates these defects by a construction featuring alow-cost structure, ease of use and maintenance, multipleinter-engageable teeth between a dog and ratchet, properly designed camsand ramps insuring increased gripping under load, easy deliberatedisengagement, maneuverability by combining a releasing device with acarrying handle, and improved stabilizing means for controlling, guidingand limiting movement of the locking dog.

The foregoing and other important objects and desirable featuresinherent in and encompassed by the invention will become apparent as apreferred embodiment is disclosed by way of example in the ensuingdescription and accompanying sheet of drawings, the figures of which aredescribed below.

FIG. 1 is a perspective view of an adjustable trestle embodying thefeatures of the invention.

FIG. 2 is an enlarged plan view, partly in section, as seen along theline 2-2 of FIG. 1.

FIG. 3 is a fragmentary side view, partly in section, as seen along theline 3-3 of FIG. 2.

FIG. 4 is a rear view of the structure shown in FIGS. 2 and 3.

The trestle selected for purposes of illustration on the basis of itspresent production and sale in commercial quantities has a generallypyramidal base made up of a plurality of steel members such as anglebars 12 and braces 14, the bars converging to and being rigidly securedas by welding at 16 to a box-like structure 18 having opposite uprightside walls 24), an upright front wall 22 spanning the side walls andrear wall means 24 including an opening 26 exposing the interior of saidstructure, which is here of rectangular section. This structure is ofrelatively substantial height to provide for adequate guiding andstabilization of an upright support member or column 28 which has at itstop a suitable saddle 30 for engagement with such supported structuresas may be encountered, e.g., vehicle axles, etc.

The member 28 is here shown as being a relatively high strength pressedsteel element of channel section, open at its front and provided at itsrear side or face 32 with a set of teeth 34, uniformly vertically spacedapart and each tooth being similar to another, each having a downwardlyfacing gripping ledge 36 and an upwardly and rearwardly facing cam face38, it being understood of course that there is a cam face 38 betweeneach pair of neighboring ledges 36. As will be seen best in FIG. 3, aplurality of teeth, in any selected position of the member 28, will beexposed rearwardly via the opening 26 to an adjoining pocket 40, whichis here provided by integral rearward extensions of the side walls 243to form a Patented Apr. 13, 1965 pair of ears 42 that project rearwardlybeyond the plane of the rear wall means 24. This pocket includes aclosed bottom 44 formed of a separate steel part welded at 46 to andspanning the ears 42. The forward lower portion 48 of this bottom may beregarded as part of the rear wall means 24, being coplanar with theupper boundary of the opening 26 and cooperating therewith and with theother walls of the structure 18 to closely but movably confine themember 28 for vertical adjustment and addi-' tionally to afford adequatestrength when the member 28 is locked in a selected position.

Selective locking of the member 28 is here achieved by a dog 50 closelyconfined by the pocket 40 and having limited vertical and fore-and-aftmovement controlled by upper and lower angled means, the latter of whichincludes a ramp 52 on the bottom 44 and a cooperating sloped surface 54on the bottom of the dog 50, and the former of which comprisescooperating guide elements respectively on the dog and on the ears 42;specifically, these guide elements include slots 56 in the ears and apin 58 Whose opposite ends enter and ride in the slots. The slots areparallel to the ramp 52, and both slope downhill toward the opening 26and of course toward which ever plurality of member teeth 34 are exposedvia the opening to the pocket 40, depending upon the vertical positionof the member 28. Since the ramp 52 and slots 56 are vertically spacedand parallel, they serve a stabilizing function that prevents cocking ofthe dog and thus confine the dog to movement such as would be achievedby parallel linkage, which is of extreme significance, as will appearlater.

The front of the dog has a plurality of teeth 60 which match or arecomplementary to the member teeth 34. Each tooth 60 has an upwardlyfacing gripping ledge 62, and a forwardly and downwardly facing cam face64 intervenes between each pair of neighboring gripping ledges 62.

The dog is here shown as being of channel-section steel but, whenequipped with a handle 66, rigidly secured thereto as by welding, hassufi'icient weight so that it gravitates downhill on the ramp 54 toautomatically eifect interengagement of the member teeth 34 and dogteeth 60. The ramp 54 and slots 56 are long enough in a downhilldirection to enable the dog to move downhill without obstruction so thatteeth interengagement is complete. It should be further noted thatseveral teeth on the member are interengaged with several teeth on thedog. In the present situation, five teeth on each element are involved.Another characteristic here is that the gripping ledges 36 and 62 arehorizontal or substantially so, whereby the force component is directlydownwardly, and this reacts against the downhill eifect of the ramp 52and undersurface 54 of the dog to force the dog not only downwardly butalso forwardly and into tighter engagement with the member 28. In otherwords, the greater the downward force or load on the member 28, thegreater the locking action of the dog on the member, thus insuringagainst accidental release of the selected lock. The interlock is ofsuch effectiveness that even though the handle 66 be accidentally jarredwhile the trestle is loaded, it is impossible to release the dog. Inthis regard, it will also be understood that the design is based onproper strength of materials etc. for the loads to be encountered, butthe particular construction (angles, type of teeth etc.) permits the useof relatively light-weight steel, thus reducing the cost of the devicewhile at the same time facilitating its use and ease of handling.

The purpose of the cam faces 38 and 64 respectively on the member anddog teeth 34 and 60 is to enable the member 28 to be moved easilyupwardly in the absence of load or force on the saddle 30, the membercam faces 38 ratcheting past the dog cam faces 64 as the dog yieldsupgarages wardly and -rearwardly'or uphill-within the limits set by therear ends of the slots 56 as engaged by the ends of the pin 58, whichlimits are designed so that, if the handle 66 is used to manually movethe dog uphill, the dogteeth will clearthe member teeth and movement ofthe member 28 canbe accomplished without ratcheting. Thus the height ofthe saddle may be easily set, and as soon as the dog is released,it-will run downhill to establish mesh of its teeth with the associatedteeth of the member. Further, because ofthe limits setby. the slots 56,the handle 66 maybe used to carry the trestle, and in this caseisproperly located with respect to the center of gravity of thestructure-as to make carrying relatively easy.

Stop means is providd to prevent separation of the column or member 28upwardly from thebase. In this case, the lower end of themember 28 hasacross pin 68between the webs of its sides, anda tab 70 is pierced fromand bent rearwardly out of the frontwallZIof the structure 18. Themember 28 cannot of course escape downwardly from thebase because thesaddle will engage the top ofthe structure 18.

Assembly of the unit is relatively easy, since the parts may befabricated byproduction-line methods and assembledby insertingthe member28-into the structure 18.

After the lower endof the member passes the structure 18, the pin 68 isinstalled. The handle 66 is p're-welded to the dog 50 and the doginstalled in. the pocket; and the guide pin 58 is passed throughtheslots 56- and through ahole drilled or punched in the dog. Reversal ofthe foregoing enables the stand or trestle to be disassembled.

Features and advantages other than those enumerated will readily occurto those versed in the art, asrwill many modifications and alterationsin the preferred embodiment disclosed, all of which maybe achievedwithout departure from the spirit and scopeof the invention.

What is claimed is: I

A trestle, comprising: abase havingabox-like structure including spacedapart upright side walls and an upright frontwall joined thereto, saidside walls respectively having ears projecting .rearwardlytherefrom andproviding a rewardly and upwardly opening pocket, upright rear upperwallmeans cross-connecting the side walls at the 4- rear thereof andabove the ears to give said structure an upper part of tubularcross-section forwardly of the pocket and leaving the pocket open at itstop, and bottom means rigidly cross-connecting the ears at lowerportions thereof and including a ramp inclined forwardly and downwardlyand termina'ting'in a downturned forward lip portion providing anupright transverse lower wall means in substantial vertical'alinementwith the rear wall means and giving said structure a lower part ofcomparable tubular cross-section spaced below said upper part to providea rear opening communicating with said pock et; an upright verticallyslidable member carried and guided by'said parts and having a rear setof uniformly vertically spaced teeth'selectively exposable to the pocketthrough said opening and said teeth being spaced apart downhill movementand tooth engagement and further so that downward force on the memberincreases toothrengagement; means including. apair of transverselyalined slots in upper portions of the ears and at an angle parallel tothat of the ramp and pin means carried by the dog and projecting atopposite ends into the slots for guiding the dog in addition to the rampand for preventing removal of the dog from the pocket,

References Cited by the Examiner UNITED STATES PATENTS 548,920 10/95Joyce 248407 1,794,052 2/31 Anderson et a1 248 -352 FOREIGN PATENTS305,984 1/31 Germany.

CLAUDE A. LEROY, PrimaryExaminer. FRANK L. AB'BQTT, Examiner.

